patterson



Feb- 7, 1956 o. l.. PATTERSON 2,734,137

cA'rHonE RAY TUBE FUNCTION GENERATOR 2 Sheets-Sheet l Filed Oct. 4. 1950 P Eou Stm NNg Feb. 7, 1956 o. l.. PATTERSON CATHODE RAY TUBE 'FUNCTION GENERATOR `Filed OCT'. 4. 1950 2 Sheets-Sheet 2 24 llo H2 |60 |86 |94 202 '56 |58 74 |82 Time new Line |96 |64 |882 Time Delay 204 [|72 |56 I (no Electronic |90 Line |98 I .l Error' Switches Time Delay 206 Ampl'f'er l Control Line 200 F /G 5 l--P- T |92 TmeDeIay |84j F'Her \|35 Llne 208 'Tl Tl 3 To Delay \/ST\2 2To Dela T L T 3 D 3 if To eay v O Delay I4 T 4 4 I gwlyll F G. 6.

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INVENToR. OMAR L. PATTERSON w, ML?

ATTORN YS.

United States Patent O Omar L. Patterson, Media, Pa., assignor to Sun Oil Cornpany, Philadelphia, Pa., a corporation of New Jersey Application october 4, 195o, serial No. 188,291 Claims. (el. 25o- 201) This invention relates to method and means for producing a cyclically repetitive arbitrary wave form as a function of time or Voltage and to apparatus involving said Wave form producing means. In particular the invention relates to the use of conventional cathode ray oscilloscope tubes for this purpose involving a minimum of complexityof apparatus and high accuracy independent to a high degree of the characteristics of said tube.

Proposals have heretofore been made to produce wave forms through the use of conventional cathode ray oscilloscope tubes by providing a mask over a portion of the face of such tube, the mask having a contoured edge conforming to the function to be generated. 'A photocell is provided responsive to the exposure of the spot produced on the oscilloscope `tube screen. The photocell through a suitable circuit was arranged to deflect the beam (for example, vertically) in such fashion that if the intensity of illumination on the photocell was too great the beam would be deflected in a direction to be further masked, While if the illumination was insufficient a reverse deflection would occur to increase the exposure of the spot produced by the beam. A properly controlled horizontal sweep of linear or other form was used with the result that the spot would follow the edge of the mask. The vertical deflecting potential during the sweep would then correspond to the function represented by the edge of the mask.

The last mentioned method of function generation, however, has various disadvantages and in particular is rather inaccurate du'e to non-linearity of the deection characteristics of the tube and aberrationsof the electron optics of the tube. In view of this la. mask could not be cut having its ordinates linearly related to the ordinates of the function to be generated with any expectation of substantial accuracy of wave form generation, and to secure even reasonable accuracy it would be necessary to exercise considerable trial and error in mask cutting with measurements of the function generated prior to each new approximation to the proper mask shape.

In accordance with the present invention there is also used a simple cathode ray oscilloscope tube with conventional low cost circuitry and a high degree of accuracy is attained substantially independent of non-linearity in deflection sensitivity of the tube and of aberrations of the tubes optical system. In brief, the invention involves the utilization of the cathode ray oscilloscope tube to produce a photographic plate or film image which is developed and then used in the reproduction by the same oscilloscope tube. By doing this and by having the plate or film located precisely in the same position during both its formation and reproduction the function generated is essentially independent of the non-linearity and aberrations just referred to. The record thus produced is permanent and usable repeatedly with the same tube when high accuracy is desired; however, the record may also be used with reasonable accuracy in conjunction with similar tubes having their deection sensitivities properly adjusted, the assumption being then made `that the optics of the reproducing tube are essentially similar to the optics of the recording tube.

If a linear time sweep is used for both recording and reproduction it will be evident that the produced function will correspond to the original and will be a function of time. However, alternatively, the record may be produced by a linear time sweep and then for reproduction there may be used a sweep function which is a non-linear function of time. In such case it will be evident that the generated function will bea function not of time but of the sweep function which Ais in turn a'function ofV time. Thus it will be evident that various complex functions may be generated.

Through the use of low persistence phosphors high frequency sweeping may be provided with generation of repetitive functions at high frequency or alternatively rapid rise times may be properly reproduced at lower frequencies.

While time of development of the photographic image represents a disadvantage, the photographic development is simpler than the cutting of a mask. Furthermore, if adjustments are desired it is easy to modify the trace on the photographic film or plate by what amounts to photographic retouching.

As will appear hereafter the original trace whichis photographed may be manually drawn. However, the photographic record may also be made if desired by applying a particular electrical wave form of either repetitive or transient type to the oscilloscope tube whereupon if desired the wave may be measured on a plotting board. The functional relationships of two wavesmay also be ascertained in similar fashion. Y"

Furthermore, as will become apparent, one or more generators of the type indicated may be used to provide input functions for differential analyzers or other computing apparatus.

It is also possible as will appear hereafter to provide superposition of functions using delay lines with the utilization of a single cathode ray oscilloscope tube and associated apparatus.

Further objects of the invention relate to improved methods and apparatus for the following of a trace by the spot of a cathode ray oscilloscope.

rl`he various general objects of the invention relate to the attainment of the results indicated above. These and other objects of the invention particularly relating to details of construction and operation will become apparent from the following description read in conjunction with the accompanying drawings, in which:

Figure l is a diagram indicating one form of the iinproved function generator;

Figure 2 is a wiring diagram showing the details of the error control portion of the apparatus indicated in Figure l;

' Figure 3y is an elevation showing a typical photographic record such as is produced and used in the generator;

Figure 4 is an elevation showing an alternative type of photographic record which may be produced and used in the generator; g

Figure 5 is a diagram illustrating the fashion in which a plurality of wave forms may be simultaneously generated using a single cathode ray oscilloscope tube; and

Figure 6 is a diagram explanatory of the operation of the apparatus of Figure 5.

Referring to Figure'l there is indicated at 2 a cathode ray oscilloscope tube of conventional type desirably having a low persistence phosphor'. The vertical deecting plates are indicated at 4 and the horizontal deilecting plates at 6. The conventional focussing, intensity, heater and other connections are indicated at 8 and are supplied from a conventional oscilloscope circuit. A lens 10 is Varranged in the axis of the oscilloscope tube to project an image of the spot from the screen upon the sensitized surface 16 of a photographic plate or film 14 supported in a holder 12. The arrangement of the physical parts of the apparatus should be such as to maintain accurately fixed the relationships of the tube 2, lens 1t) and holder `12, the latter being. so arranged as to receiveV an hold precisely in position the sensitized element 14 which, for the purpose of securing maximum accuracy, is dcsirably a sensitized plate. Film however, may be used preferably with aligning holes for the reception of pins to maintain it accurately positioned and render it capable of being returned to its initial position` after removal therefrom. As` will be apparent hereafter, it is of importance that the sensitized element after development may be located precisely in the` position in which it was exposed for thc making Vof a trace thereon.

O ne ofthe surfaces of the sensitized element 14-should be formed as a diffusing` surface or, alternatively, the sensitized element may be associated with a diffusing translucent surface as may be provided by ground glass. Beyond the element 14 there is provided the` collecting lens. 18 to project therimage of a spot from this diffusing .surface on the cathode of a photocell indicated at 20. Insteadv of projecting the image of the spot on the sensitized element upon the photocell, it has been found very satisfactory to use a sensitized element of small area and to merely back it up with a photocell, thus eliminating lens 18. As will appear hereafter, variation of level of illumination of the photocell by the exposed spot is not particularly important so that the arrangement just described is quite practical.

In order to provide sufficient sensitivity the photocell 20 generally should be of multiplier type. In any event it is associated with a conventional video amplifier 22 which provides its output at terminal 24vto an error control .26 which will be hereafter more fully described with reference to Figure 2. The output terminal 28 of the error controlis connected to the contact point 3i) of a single-pole double-throw switch 32, the other Contact point 34 of which is connected to a terminal 36 for the e application of an external arbitrary voltage. The switch 32 is connected through line 38 tothe contact point 40 of a single-pole double-throw switch 42 which is connectedthrough line 44 to the direct current amplifier 46 forKvertical deflection of the beam of the cathode ray tube. A similar direct current amplifier 48 `is provided for horizontal deflection of the beam and lreceives its input through connection 50 `from a single-.pole doublethrow switch 52, the contact 54 of which is connected through. switch S6 alternatively to contact point 58 and i terminal` for kthe application of any desired horizontal sweep or to the contact point 62 which is connected to the conventional linear horizontal sweep generator 64 having a synchronizing connection 66 for the reception of a synchronizing signal.

The video amplifier z2, the amplifiers 46 and 4s and the linear horizontal sweep generator 64 vmay be conventional and are accordingly not described in detail.

For the purpose of providing vertical and horizontal defiection for the tracing of a curve on the sensitizet member 14 there is provided the manually operable arrangement shown at the lower left of Figure l.

A board 68 provides a support for a sheet 70 on which there may be traced and followed a curve A corresponding to the wave form to be generated. A stylus 72 adapted to be moved to follow the curve A has sliding mounting in the slots 74 and 76 of members 78 and 80 provided with cross heads 82 'and 84 'mounted to slide in rectangular directions in guidcways 86 and 88 in the board. The cross head 82 carries the contact 90 of a linear potentiometer 92 connected between a positive potential source and ground. Similarly the cross head 84 carries a contact 94 of a linear potentiometer 96 also connected between a positive voltage supply and ground. Itwill beevident-that the arrangement just described provides, when the stylus 72 follows acurve such as A potentials at contacts and 94 which are linearly related respectively to the ordinates and abscissae of curve A. Suitable voltmeters 98 and 100 may be provided to indicate these potentials. The contact 90 is connected to the contact point 162 of the switch 42 heretofore described while the contact -94 is connected to the contact point 164 of the switch 52 also heretofore described.

The connection 44 is joined to the input of a low pass filter 106 which has av cut off higher than the maximum requeney component ofthe output wave form, the output terminal of this filter being indicated at 108. As will appear hereafter the output at connection 44 is in the form of the wave to be reproduced having superimposed thereon a high frequency saw tooth wave form which is filtered out by the filter 106, leaving the wave form desired.

The error control 26 is detailed in Figure 2. The input from terminal 24 is delivered through condenser 110 to a cathode follower arrangement comprising the triode 112 and suitable cathode resistance which, in turn, provides an output through connection 114 to the bistable multivibrator comprising the pentodes 116 and 118. The circuit of this bistable multivibrator or scaling circuit is substantially conventional except' for certain limiting arrangements which appear therein. The cathodes of pentodes 116 and 118 are connected together and to ground through avseries of resistances 120, 122 and 124. As is usual an essentially constant current flows through these resistances. The anodes of the pentodes are respectively connected to the positive potential supply line through resistances y126 and 128 and criss-cross connections between each anodev and the grid of the companion tube are providedby the resistance-capacitance networks indicated at 130 and 132. Connection 114 is to the screens of the pentodes 116 and 118. Diodes 134 and V136 arranged as illustrated are connected between the screens andthe anodes of the pentodes. In order to provide voltage limitation there are connected between the grids ofthe pentodes `and the junction points of the resistances-120, 122 and 124 the crystal diodes 138, 149, 142 and 144 polarized as indicated. The result is that the potential of-a control grid cannot rise above the potential of the junction point of resistances and 122 and cannot fall below the potential of the junction point of the resistances 122 and 124. In this fashion limited, substantially squarewaves are emitted when the bistable multivibrator is thrown from its one stable condition to the other. A negative pulse on the line 114 serves to trigger the multivibrator in the usual fashion.

The output 'of the multivibrator isrdelivered from the anode of pentode 118 through condenser 146 and a resistance network including the resistance 14S to the grid oftriode 150. A resistance 151-connects the anode of triode 156Mo the Ypositive Apotential supply line and there is connected between 'the' anode fand grid of triode 150 the condenser 152, the arrangement 'being such that the circuit of this triode constitutes an integrator which provides a triangular output with the amplitude of its excursions dependent uponthe time vof duration of the respective stable states of the multivibrator.`

The operation of the described system is as follows:

The predetermined wave form A may be either drawn to a desired scale on the sheet 70 or more accurately may be plotted thereon while lthe yplotter observes the readings of voltmeters` 98 and 100 to determine the position of the stylus 72 corresponding to the ordinates and abscissae of points on the wave form which may be known. If a point by point plottingis thus effected by reference to the voltmetersthere mayfollow such plotting the drawingof a smooth curve; ifY the wave form is desirably smooth, orof broken 1ines,vor the like, if otherwise, between the plotted-fpoints Inany event by the use of accurate voltmeters -itfwill be-evident that the curve may be provided on the sheet 70 so as 4to eliminate any errors of linearity of the potentiometers 92 and 96.

Following the production of the desired curve, the switches 42 and 52 are located in their left-hand positions illustrated in Figure l and there is placed in the holder 12 a` sensitized photographic element 14 of the type described. If now the operator follows one or more times the curve A by the stylus `72, the light spot of the oscillograph tube will trace on its screen a curve corresponding to the curve A and the image of the spot will be projected to expose the sensitized element. The tracing may be carried out sufficiently slowly to produce the desired exposurein one tracing of the curve, or if a denser exposure is desired the curve A may be repeatedly traced. j

The exposed element 14 may then be developed to a high contrast to produce a curve such as T in Figure 3 representing the trace corresponding to the original at A. This image is then fixed and otherwise finished in conventional photographic fashion.

Generally it will then be desirable to cover regions `above and below the trace T with photographic opaque coating such as indicated at S and S' in Figure 3, leaving a transparent region of limited extent both above and below the trace T.

The wave form may now be reproduced by the apparatus, the developed photographic record being placed therein in the position occupied during exposure. Assuming that a direct reproduction of the preciseV wave form originally drawn is to be effected, the switch 56 is located in its right-hand position illustrated in Figure l to be connected to the linear horizontal sweep generator 64. The switches 42 and v52 are also located in their right-hand positions. r[he switch 32 is located in its upper position indicated in Figure 1.

Operation of the apparatus then occurs in the following fashion:

An initial impulse may be imparted to the light spot of the oscillograph tube to cause it to move vertically so that its projected image on the photographic member 14 moves correspondingly vertically. As the spot crosses the trace T an impulse will be transmitted from the photocell through the video amplifier to the error control.V Assuming that the number of stages in the video amplifier is such that the obscuring of the spot momentarily by the trace T gives rise to a negative trigger pulse at the input tothe scaling circuit, the scaling cir- Y cuit will be thrown to its alternative stable position producing a square wave output which through the integrator will produce anV excursion of the spot projected on the record member 14 in an opposite direction. As the spot again crosses the trace T the scaling circuit will again be lipp'ed causing, through the integrator, a reversal of the movement of the spot. AsV these excursions in reverse direction occur, with reversal after each passage of the projected spot across the trace T, the horizontal sweep will be moving the spot horizontally.

l The result is that the spot will follow the trace T zig-zagging across this trace at a high frequency. The circuit adjustments should be so setV that this frequency of reversal is substantially greater than the highest frequency which it is desired to reproduce, and preferably constants are-so chosen that the spot image departs very little from trace T above and below the same; i. e., the amplitude of the zig-zag wave should be small in the interest of maximum accuracy of reproduction. The potentials applied for vertical deflection are transmitted through the filter 106 which will cut off the frequency of the triangular zigf zagwave'so that there will be reproduced at terminal 108 a smoothed output corresponding to the original trace A.

As will be evident by adjustment of the frequency of the -horizontal sweep the repetitive frequency of this output may be adjusted to any desired value short of the situwave would be lost by their rise beyond the cut-off point of lter 106.

It will be,evident that if the record traceT is made as aforementioned the output will correspond very precisely to the original traced curve A entirely independently of the aberrations and non-linearities of the oscilloscope tube, the amplifiers, or the optical lens system. This result, of course, follows from the placement of the record member 14 in the same position for both recording and reproduction. It may, in fact, be noted that while a low persistence phosphor is desirable, the system is more tolerant, in its operation, of longer persistence, as compared with a system which requires the oscilloscope spot to ride, partially obscured, the edge of a mask. For a given persistence phosphor, therefore, higher reproduction frequencies are possible.

The purpose of the opaque coating provided over the areas S and S may now be described. If in the excursion of the projected spot upwardly across the trace T it should happen that before reversal it passed over a speck of dust, or there occurred some other possible electrical disturbance which might be equivalent to opacity in its eifect on the error control, the projected spot might continue to move upwardly rather than be reversed to move downwardly across the trace. In order to insure reversal the opaque coating is provided to form an edge above the trace which will produce occultation of the spot and effect reversal whereupon after the spot again crosses the trace the zig-zag following of the trace should continue in normal fashion. The same effect, of course, occurs if the spot travels too far downwardly, the reversal then occurring when it crosses the upper edge of the lower area S of the opaque coating. lt will be evident that this same effect of maintaining the spot normally on the trace may be attained by electrical limiting means which will reverse the spot whenever the vertical deflection potential becomes either too high or too low. The same type of operation may be effected electrically by providing that if the excursion in a given direction occurs for more than a limited period a reversal will occur. In such fashion proper tracing is, in general, securable,

vthe uncontrolled excursion merely providing a momentary transient which is at such frequency as to be eliminated in any case by the filter 106 without substantial deviation from the true wave form. It may be noted furthermore that it would generally be probable that such an improper excursion of the spot would only occur through one cycle if occasioned by some electrical disturbance as compared with a speck of dirt physically on the member 14.

The record may be made otherwise than as illustrated in Figure 3, for example, as illustrated in Figure 4. ln this case vertical deflection of the spot is under control of a high frequency signal, the frequency being much greater than the period of tracing or formation of the record so as to give complete exposure of the entire area under the curve. If the vertical dellecting potential is then limited by the output, for example, from the plotting board there will be produced a blackened area upon development which, as illustrated in Figure 4, will have the sharp upper boundary T having the form of the function being recorded. Devices for limiting the excursions of a high frequency potential are well known and need not be described.

In using the developed record of the type illustrated in Figure 4, the error control should be of a type different from that illustrated in Figure 2 and may be of the monostable multivibrator type in which an impulse signal produced by an upward excursion of the spot across the boundary T will throw the multivibrator to its unstable state from which it will return after the lapse of a predetermined interval. The result would then be a zigzag path of the spot following the boundary T' in the form of an approximately rectangular wave, the upper limits of which may be slightly above the boundaryT delivered through amplifier 172 to the vertical deecting plates of the oscilloscope tube 156. Except for the mei chanical arrangements, what has just been described may be similar to what has been described in connection with Figure 1.

A trace 174 corresponding to T of Figure 3, may be recorded as in the case of apparatus previously described on the photographic element 160 which is then developed and fixed. During the plotting of the curve 174 the horizontal variation may be secured by controlling mechanically the angular rotation of the disc past the line in which the projection of the spot moves. On the periphery of the disc there may be then marked, for example, radial lines 176 delimiting various segments of the curve 174 which has heretofore been referred to as a continuous one. However, continuity would not be normal in this apparatus and, instead, the complete curve 174 would be made up in the form of segments each of which would correspond to a separate function, all of which functions are later to be reproduced in the same period of time.

The markings 176 are arranged to occult the light from a lamp 178 falling on a photocell 180 which controls an electronic switching arrangement illustrated at 182. This arrangement may be conventional, consisting of a repetitive counting system controlling a number of electronic switching tubes corresponding to the numberV of functions to be simultaneously reproduced and incorporated in the curve 174. The input to the electronic switches is from the'error control 170 through connection 184 including the low pass filter 18S corresponding to 106 of Figure l.

The outputs from the switches are delivered through connections 186, 188, 190 and 192 to the time delay lines 194, 196, 19S, and 200 respectively from which outputs are delivered at respective terminals 202, 204, 206 and 208.

The operation of the system just described may be made clear by considering Figure 6. The curve 174 which is subjected to scanning by the spot image may be considered to be made up of the separate functions T1, T2, T3 and T4 which follow each other in serial fashion. These various functions are switched to respective delay lines which have delays related to the period To of duration of each of the functions and corresponding to ST0, 2To, To, and O.

(The last, of course, is merely a direct connecting line, and has been referred to as a time delay line merely for generality, since all of the functions may, if desired, be subject to additional delays.) r

As will now be evident the use of the switching arrangement and the delay lines will result in the emission at the various terminals of al1 of the functions during the same period which will correspond to the period in which the function T4 is generated.

It will thus be evident that a single oscilloscope assembly may be used for the generation of a number of functions which are to be simultaneously supplied to an apparatus such as a computer. This, of course, presupposes that the active part of the cycle of repetition of the computer is sufficiently short so that its inactive portion will accommodate properly the serialvgeneration of all of the functions to be provided.

It will be evident from the foregoing that numerous variations may be made in the embodiments of the invention without departing from the scope thereof as defined in the following claims.

What is claimed is:

l. The method of function generation utilizing cathode ray oscilloscope apparatus providing an illuminated dot dellected in accordance with electrical signals introduced to said apparatus, whichV method comprises mounting a sensitized photographic element in the path of said dot, electrically producing deflection of said dot to record on said element a latent line image, providing from said element a member providing a visible line having the shape 10 and size of said latent line image, mounting said 'member with said visible line occupying relative to said apparatus the position which was occupied vby said latent line image at the time of recording, and electrically producing deection of the dot provided by said apparatus under control of photoelectric means arranged, in response to illumination from said member due to said dot, t0 cause said dot to follow a path related in predetermined fashion to said visible line. Y

2. vThe method of function generation utilized cathode ray oscilloscope apparatus providing an illuminated dot deflected in accordance with electrical signals introduced to said apparatus, which method comprises mounting a sensitized photographic element in the path of said dot, electrically producing deliection of said dot to record on said element a latent line image, providing from said element a member providing a visible line having the shape and sizeof said latent line image, mounting said member with said visible line occupying relative to said apparatus the position which was occupied by said latentline image at the time of recording, and electrically producing deflection of the dot provided by said apparatus under control of photoelectric means arranged, in response to illumination from said member due to said dot, tocause said dot to follow said visible line.

3. The method of function generation utilizing cathode ray oscilloscopeapparatus providing an illuminated dot deected in accordance with electrical signals introduced to said apparatus, which method comprises mounting a sensitized photographic element in the path of said dot, electrically producing deflection of said dot to record on said element a latent line image, providing from said element a member providing aV visible line'having the shape and size of said latent line image, mounting said member with said visible line occupying relative to said apparatus the position which was occupied by said latent line image at the time of recording, and electrically producing deflection of the dot provided by said apparatus under control of photoelectric means arranged, in response to illumination from said member due to said dot, to cause said dot to follow a zig-zag path along and crossing said visible line.

4. The method of function generation utilizing cathode ray oscilloscope apparatus providing an illuminated dot deflected in accordance with electrical signals introduced to said apparatus, which method comprises mounting a sensitized photographic element in the path of said dot, electrically producing deflection of said dot to record on said element a latent line image, providing from said element a member providing a visible line having the shape and size of said latent line image, mounting said member with said'vsible line occupying relative to said apparatus the position which was occupied by said latent line image at the time of recording, electrically producing deflection of the dot provided by said apparatus, and producing an electrical output from photoelectric means arranged for response to illumination from said member due to the relationship of said dot to said visible line.

5. In combination, cathode ray oscilloscope apparatus providing an illuminated dot and having terminals for the reception of signals for deflection of said dot, means for mounting a sensitized photographic element in the path of said dot, first means for introducing signals to said terminals for the deflection of said dot for the production thereby of a latent line image on said element, said mounting means serving also for the mounting of a member providing a visible line having the shape and size of said latent line image with said visible line occupying relative to said apparatus the position which was occupied by said latent line image at the time of its production, second means for introducing signals to said terminals for the deection of said dot, said second means comprising a sweep generator and photoelectric means constructed and arranged, in response to illumination from such mounted member due to said dot, to cause said dot to follow a path related in predetermined fashion to said manna? visibleV line;` .andswitching means for alternatively"andI selectively providing :to .said .terminals either :signals `,from

saidrst'rneansorfrom said second means.l

6. In combination, cathode',rayoscilloscope .apparatus providingan yilluminated dot and'having, terminals fof the reception of sigualsfor -deection-ofzsaid dot, means for mounting a sensitizedzphotographic .element Vin the path of said dot, rst means for introducingsignals to said terminals for the deflection of said dot for the production thereby of .a latent line.image on'said element, said mounting means servingxalsofor the mounting of a mem ber providing a visible line'having; the shape and size of saidlatent line image with said-visible yline occupying relative to said apparatus theposition which was occupied by said latentline .image at the time yofits production, second means for introducing signals to said terminals .for thel deilcction `of said dot, said second vmeans .comprising a sweep generator and photoelectric means constructed and arranged, in response to illumination from such mounted memberdue to said dot, to cause said dot to follow said visibleline, and switching-means-for alternatively and selectively providing'to said `terminals either signals from said-iirst means orf-from said, second means.

7. In combination, cathode rayoscilloscope apparatus providing an illuminatedvdot and having terminals for the reception'of signals :for deliection of said dot, means for mounting a sensitized photographic element `in the path ofsaid dot, iirst means for introducing signals to said terminals for the deflection of said dot for the production thereby of a latent line image on said element, said mounting means serving also for the mounting of a member providing a lvisible line having the shape and size of said latentline'image-with said visible line occupying relative to said apparatus the position which was occupied by said latentline image at the time of its production, second means for introducing lsignals to said terminals for the deflection of said dot, said second means comprising photoelectric means constructed and arranged, in response to illuminationfrom such mounted member due to said dot, to cause said'dot to follow a path related in predetermined fashion'to said visible line, and switching means for alternatively and selectively providing to said terminals either signals from said first means or from said second means.

S. ln combination, cathode ray oscilloscope apparatus providing an illuminateddot and having terminals for the reception of signals for deflection of said dot, means for mounting a sensitized photographic element in the path of said-dot, first manually controlled means for introducing signals to said l,terminals for the deflection of said dot for the production thereby of a latent line image on said element, said mounting means seta/ing also for the mounting of a member providing a visible line having the shape and'size of said latent line image with said visible line occupying relative to said apparatus theY position which was` occupied by said latent lline image at the time of its production, second means for introducing signals tosaid terminals for the deflection of said dot, said second means comprising a sweepA generator and photoelectric means constructed and arranged, in response to illumination from such mounted member due to said dot, to cause said dot to follow a path Cit related-.in predetermined fashionto saidvisibley line; andswitching ,means-for alter-natively and; selectively provideing tosa'idzterminals zeither signals from said rtirst `'means or-fromsaid second means.l

9. In combination, cathode ray oscilloscope apparatus providing .anpilluminated dot -Vand having :terminals for the reception oft-signals :for-deflection of said dot, means ifor mounting asensitized"photographic element in the path of said'dot, tirstmanually controlled means for introducing-signals to said terminals for the -decction orsaid dot for the productiongthereby of a latent line imageon said element, saidfmounting means serving also for the mounting of .al member providing a visible line having the shape, andsizefofsaidjlatent line image with'V said visible line occupying relative to` said apparatusvthe -positionwhich was occupied by-said latent line image'atthe time of its production,4 second'means for introducing signals' to said terminals for the detlection of said dot, saidfsecondqmeans comprising photoelectric means con'- structed and arranged', in 4response to -illuminationxfrom such mounted member due to said dot, to cause saidfdot to` follow apath lrelated in predetermined fashion'zto, said visible line, andvswitching means for alternatively and selectively providing tosaid terminals either signals from said tirst means orv from said second means.

10. In combination, cathode ray oscilloscope apparatus providingran,illuminated dot and having terminals for the reception of'signals for detiection of said dot, means for mounting a sensitized photographic element in thepath of'said dot, first'means for introducing signals to `said terminals forthe deection of said dot for the production thereby of a latent line image on said element, said mounting means serving also for the mountingof a membervproviding avisble'line having the shape and size of said latentlineimage with `said visible line occupying relative to said apparatus the position which was occupiedibysaid latent line image at the time of,its production,tsecondfmeans for introducing signals to said terminals for the. deection of said dot, photoelectric meansconstructed and arranged, in responseto illuminationrfrom such mounted member due to said dot, lto vprovideanelectrical outputrhaving values functionally related to the ordinates of said visible line, and switching means for-alternatively and selectively providing to said terminals either signals from said first means-or from said second means.

References Citedein the file of this patent UNITED STATES PATENTS 1,894,637 Scheibell Ian. 17, 1933 2,075,140 Schlesinger Mar. 30, 1937 2,171,216' Koch Aug. 29, 1939 2,251,525- Rosenthal Aug. 5, 1941 2,236,222 Smyth Mar. 25,'1941 2,455,532 Sunstein Dec. 7, 1948 2,462,263 Haynes Feb. 22, 1,949 2,548,590 Cook` Apr. l0, 19,51 2,575,445" Germer Nov. 20, 195i FOREIGN PATENTS 817,910 France lune 7, 1937 

